Month: May 2017

Hold a buttercup flower under your chin. If your chin glows yellow, you love butter. That is according to a classic childhood game anyway. Recent research explored the cellular structure of buttercup petals and revealed the anatomical reason behind their yellow glow. Apart from helping to warm the flower’s sex organs, this glow is thought to draw in pollinating insects to ensure proper pollination.

Now take the fresh green leaves of buttercups, crush them up, and rub them against your skin. On second thought, DON’T DO THAT! This is not a childhood game and should absolutely be avoided…unless, of course, you derive some sort of pleasure from painful blisters.

Buttercups, also commonly known as crowfoots, are in the genus Ranunculus and the family Ranunculaceae. Ranunculus consists of a few hundred species and is a common group of annual and perennial herbaceous plants with alternately arranged, palmately veined leaves that are either entire, lobed, or finely divided. Buttercup flowers are usually yellow (sometimes white) with 5 petals (sometimes 3 or 7) that are either borne singly or in loose clusters. The flowers are complete, having both male and female reproductive structures that are easily identifiable. Flowering usually occurs in the spring.

Ranunculus species are found throughout the world. Common habitats include moist woods, meadows, open fields, wetlands and other riparian areas, as well as drier sites like roadsides and neglected, urban lots. Several species are commonly grown as ornamentals, and others are common weeds in natural areas, urban landscapes, and agricultural fields.

All buttercups contain a compound called ranunculin. When the leaves are crushed or bruised, ranunculin breaks down to form an acrid, toxic oil called protoanemonin. Contact with this oil causes dermatitis. Symptoms occur within an hour of contact and include burning and itching along with rashes and blisters. When the leaves are chewed, blisters can form on the lips and face. If swallowed, severe gastrointestinal irritation can follow, accompanied by dizziness, spasms, and paralysis. The toxic oil is also irritating to the eyes.

Ranunculus species vary in their levels of this toxic compound, and individual plants are said to be more toxic in the spring when they are actively growing and flowering. Protoanemonin breaks down further into an innocuous compound called anemonin, so dead and dried out plants are generally safe. Commonly encountered (and particularly toxic) species in North America include tall buttercup (R. acris), cursed buttercup (R. sceleratus), creeping buttercup (R. repens), littleleaf buttercup (R. arbortivus), and sagebrush buttercup (R. glaberrimus). Bulbous buttercup (R. bulbosus) has bulbous roots that are toxic when fresh but are said to be edible after they are well boiled or completely dried.

cursed buttercup (Ranunculus sceleratus)

The toxicity of Ranunculus species seems to be more of an issue for livestock than for humans. Grazing animals tend to avoid it since it tastes so bad. Those that do eat it exhibit responses similar to humans – blistering around the mouth, gastrointestinal issues, etc. In The Book of Field and Roadside, John Eastman writes about Ranunculus acris: “Cattle usually avoid the plant – its acrid juices can blister their mouths – though they can also develop something like an addiction to it, consuming it until it kills them.” Buttercups becoming dominant in pastures and rangelands is often a sign of overgrazing.

Despite – and likely due to – their toxicity, buttercups have a long history of medicinal uses. Civilizations in many parts of the world have used the leaves and roots of the plant to treat numerous ailments including rheumatism, arthritis, cuts, bruises, and even hemorrhoids. A report published in 2011describes three patients in Turkey that had applied poultices of corn buttercup (R. arvensis) to parts of their body to treat rheumatism. The patients were treated for chemical burns caused by the applications. The report concludes by advising against treatments “whose therapeutic effects have not been proven yet by scientific studies.”

In The North American Guide to Common Poisonous Plants and Mushrooms, buttercups are listed among plant species that are skin and eye irritants, honey poisons, and milk poisons (see Appendices 3, 4, and 5). Other genera in the buttercup family may also contain high levels of protoanemonin, including popular ornamentals like Clematis, Helleborus, Anemone, and Pulsatilla. Thus, the moral of this story: handle these plants with care.

In the early 1800’s, seeds of purple loosestrife found their way to North America. They arrived from Europe several times by various means – accidentally embedded in the ballast of ships, inadvertently tucked in sheep’s wool, and purposely carried in the hands of humans. Native to much of Europe and parts of Asia and commonly found growing in wetlands and other riparian areas, purple loosestrife’s appealing spikes of magenta flowers, sturdy, upright growth habit, and ease of propagation made it a prized ornamental; its abundant nectar made it a favorite of beekeepers.

During its first 150 years or so in North America, purple loosestrife became naturalized in ditches, wet meadows, and the banks of streams, rivers, lakes, and ponds while also enjoying a place in our gardens. Concern about its spread was raised in the first half of the twentieth century, but it wasn’t until the 1980’s after an extensive survey was done and a special report was issued by the U.S. Fish and Wildlife Service that attitudes about purple loosestrife shifted dramatically. At that point, it was no longer a benign invader and welcome garden companion. It was, instead, a biological menace that needed to be destroyed.

Lytrhrum salicaria – commonly known as purple loosestrife, spiked willow-herb, long purples, rainbow weed, etc. – is an herbaceous perennial in the family Lythraceae. It reaches up to two meters tall; has square or angular stems with lance-shaped, stalkless leaves up to ten centimeters long; and ends in dense, towering spikes of pink-purple, 5-7 petaled flowers. The flowers attract a wide variety of pollinating insects – mostly bees – and afterwards produce small capsules full of tiny, red-brown seeds. Charles Darwin thoroughly studied the flowers of purple loosestrife; he was intrigued by the plant for many reasons, including its heterostyly(a topic for another post).

Purple loosestrife seeds remain viable for up to 20 years and are transported by wind, water, and in mud stuck to the feet of birds. Apart from seeds, populations expand clonally as root crowns grow larger each year and produce increasingly more stems. Broken stem pieces also take root in mud, creating new plants. Purple loosestrife’s ability to form expansive populations in a quick manner, pushing other plants aside and forming what appears to be a dense monoculture, is part of the reason it has earned itself a place among the International Union for Conservation of Nature’slist of 100 World’s Worst Invasive Alien Species.

But is this ranking justified? In a paper published in Biological Invasionsin 2010, Claude Lavoie compares news reports about purple loosestrife around the turn of the century with data presented in scientific papers and finds that the reports largely exaggerate the evidence. Purple loosestrife was being accused of all manner of crimes against nature and was being condemned before there was sound evidence to justify such actions.

It began with the U.S. Fish and Wildlife Service’s special report published in 1987. According to Lavoie, “a long list of the impacts of the species on wetland flora and fauna [was] presented,” but the claims were not supported by observational or experimental data – “the impacts [were] only suspected.” Regardless, wetland managers began campaigns against purple loosestrife in order to convince the public that it was a Beautiful Killer. News outlets were quick to spread the word about this “killer” plant. When biological control programs began in the 1990’s, news outlets reported on their success. Little empirical evidence had been published on either topic, and debates about purple loosestrife’s impacts remained unsettled in the scientific community.

Around this time, five reviews were published examining the evidence against purple loosestrife. Lavoie reports that all but one of them “rely on a relatively high number of sources that have not been published in peer-reviewed journals.” After examining the reviews, Lavoie concludes: “although each review provided valuable information on purple loosestrife, most were somewhat biased and relied on a substantial amount of information that was anecdotal or not screened by reviewers during a formal evaluation process. Only one review was impartial, and this one painted an inconclusive picture of the species.”

Research has continued regarding the impacts of purple loosestrife, and so Lavoie examined 34 studies that were published during the 2000’s in search of conclusive evidence that the plant is as destructive to wetlands and wildlife as has been claimed. Upon examination he concludes that “stating that this plant has ‘large negative impacts’ on wetlands is probably exaggerated.” The most common accusation – that purple loosestrife crowds out native plants and forms a monoculture – “is controversial and has not been observed in nature (with maybe one exception).” Lavoie finds that there is “certainly no evidence that purple loosestrife ‘kills wetlands’ or ‘creates biological deserts,'” and “there are no published studies [in peer-reviewed journals] demonstrating that purple loosestrife has an impact on waterfowl or fishes.” All other negative claims against purple loosestrife “have not been the object of a study,” except for its impact on amphibians, which had at that time only been tested on two species, one “reacting negatively.” Certain claims – such as purple loosestrife’s impact on wetland hydrology – should be studied more in depth “considering the apparent public consensus on the detrimental effects of purple loosestrife” on wetland ecosystems.

Lavoie agrees that it is reasonable to control purple loosestrife when the intention is to reduce additional pressures on an ecosystem that is already highly threatened. However, he warns that “focusing on purple loosestrife instead of on other invasive species or on wetland losses to agriculture or urban sprawl could divert the attention of environmental managers from more urgent protection needs.” There is mounting evidence that purple loosestrife invasions are disturbance-dependent and are “an indicator of anthropogenic disturbances.” In order to protect our wetlands, we must first protect them against undue disturbance. Lavoie supports using the Precautionary Principle when dealing with introduced species; however, he finds the approach “much more valuable for newcomers than for invaders coexisting with native species for more than a century.”

Purple loosestrife has found its way to nearly every state in America and most of the Canadian provinces. Peter Del Tredici writes in Wild Urban Plants of the Northeast, “Conservationists despise purple loosestrife, despite its beauty, and it is listed as an invasive species in most of the states where it grows.” By listing a plant as a noxious weed, landowners are obligated to remove it. Care must be taken though, as removal of purple loosestrife can result in a secondary invasion by noxious weeds with an even worse track record, such as common reed or reed canary grass. “Hardly a gain from the biodiversity point of view,” quips Lavoie.

Claude Lavoie’s paper and the papers he references are definitely worth reading. It is important that we continue to study purple loosestrife and species like it in order to fully understand the impact that introduced species are having on natural areas, especially since it is unlikely that we will ever completely eliminate them. On that note, I’ll leave you with this passage from The Book of Swamp and Bog by John Eastman:

The situation is easy for environmentalists to deplore. This plant, like few others, stirs our alien prejudice. Our native cattails, for example, are almost as rudely aggressive and competitive in many wetland areas as purple loosestrife. Yet, because cattails obvioulsy ‘belong here,’ they seldom evoke the same outraged feelings against their existence. … With the spread of purple loosestrife, we have new opportunities to witness the phases of an ever-recurring ecological process. We can watch it affect, change, adapt, and refit both its own elements and those of invaded communities into new arrangements of energy efficiency. The point is that we might as well study this process rather than simply deplore it; we have few alternatives.

Thanks to an invitation from my girlfriend Sierra and her family, I spent the first weekend in May exploring Yellowstone National Parkby way of Chico Hot Springsin Pray, Montana. The weather was perfect, and there were more plants in bloom than I had expected. During our hikes, my eyes were practically glued to the ground looking for both familiar and unfamiliar plant life. Most of the plants in bloom were short and easily overlooked. Many were non-native. Regardless, the amateur botanist in me was thrilled to be able to spend time with each one, whether I was able to identify it or not. I tried to remind myself to look up as often as I was looking down. Both views were remarkable.

On our first day there, we hiked in the hills above Chico Hot Springs. The trail brought us to a place called Trout Pond. There were lots of little plants to see along the way.

The next day we drove into Yellowstone. From the north entrance we headed east towards Lamar Valley. Wildlife viewing was plentiful. Elk, bison, bighorn sheep, pronghorn, black bears, red foxes, and even – if you can believe it – Canada geese.

On our third day there, we headed south to see some geysers. We made it to the Norris Geyser Basinand then decided to head east to see the Grand Canyon of the Yellowstone. This was our geology leg of the tour. But that doesn’t mean we didn’t stop to look at a plant or two along the way.

One of the biggest threats to wetland ecosystems is, of course, invasive species. In last week’s postI shared a selection of videos that were produced by a variety of organizations to inform the public about invasive species. Many such videos specifically address invasives in wetlands and waterways. Here are a few of those videos.

I have been posting almost exclusively about invasive species for four months now. If you have made it this far, I salute you. It is neither the most exciting nor the most encouraging topic, but it is the journey I am on (for whatever reason), and I am pleased to have you along.

In the battle against invasive species, citizen awareness and participation is imperative. The public and private sectors can try as they may, but if individual citizens are acting in ways that help introduce or spread invasives, then much of this effort can be for naught. Thus, campaigns to educate the public are regularly launched.

One popular way to spread the word is through video. Often, the goal of these videos is to both educate and entertain. Some achieve this better than others, while some are downright dull or simply baffling. Speculating on the effectiveness of these videos is not the purpose of this post. Rather, I just thought I would take a break from the usual text heavy posts and share a few videos that I found interesting and/or entertaining. If you have a favorite invasive species video, please share it in the comment section below.